商品名：T4, L-thyroxine, Soloxine, Thyro-Tabs, Synthroid,
Thyroid hormone. Levothyroxine is used as replacement therapy for treating patients with hypothyroidism. Levothyroxine is T4, which is converted in most patients to the active T3. Requirements and pharmacokinetics vary among animals and doses are adjusted on the basis of thyroid monitoring. Levothyroxine has a half-life of approximately 20 hours in dogs.
Levothyroxine is used for replacement therapy in animals with thyroid hormone deficiency (hypothyroidism). It has been used in many species, including dogs, cats, and horses. Although it has been suggested for use in treating dogs with von Willebrand’s disease, clinical studies failed to show an effect on clotting factors, bleeding times, or von Willebrand’s factor (vWf) from levothyroxine treatment (0.04 mg/kg). Intravenous levothyroxine sodium may be used in dogs for acute treatment of hypothyroid dogs with myxedema coma (4-5 mcg/kg IV).
劑量數字暫停提供：VetPro 的劑量改依 DRUGAPI 藥物資料庫對外的內容，DRUGAPI 目前不提供可直接計算的劑量。下方列出 DRUGAPI 的審查結論與劑量審查引用的來源；計算機可手動輸入劑量換算。
先確認患者物種、低甲狀腺診斷型態與非甲狀腺疾病或藥物造成的檢驗干擾 鎖定精確產品、劑型、強度、食物狀態與法域，不可跨產品換算 依精確產品標籤與實驗室方法規劃臨床反應、甲狀腺檢驗與調整 先處理未矯正的腎上腺功能不足並評估心血管、糖尿病與共同用藥風險
DRUGAPI 劑量審查引用的獸醫官方標示（各標示只適用於其產品、物種與法域，不可互換）
依出現頻率分組；嚴重副作用獨立列出，臨床上需立即辨識。